Sensor network nodes are used in many applications. For example, sensor network nodes are used to monitor: seismic activities; atmospheric pressure, temperature and humidity; indoor and outdoor agriculture to increase yield; environmental variation on a fine grained scale; vibration in factories to predict machine failures; a ship's hull for cracks in a distributed fashion; and HVAC systems in large office buildings.
FIG. 1(a) is a block diagram of a conventional sensor network 100(a). The sensor network 100(a) can be used in many applications such as, for example, detection of sound, radiation, pollution, etc. The sensor network 100(a) includes a plurality of nodes 104(a), 108(a), 112(a), and 116(a). The nodes 104(a)-116(a) communicate with each other wirelessly. The sensor network 100(a) includes a base station 124(a) that communicates with the nodes 104(a)-116(a) wirelessly.
FIG. 1(b) is a block diagram of a conventional sensor network 100(b) where the nodes 104(b)-116(b) are connected to each other by a communication link 120, such as a wired link, an optical link, the Internet or any other communication link. The nodes 104(b)-116(b) can communicate with each other over the communication link 120. The sensor network 100(b) includes a base station 124(b) that communicates with the nodes 104(b)-116(b) over the communication link 120. The nodes 104(a)-116(a) and 104(b)-116(b) monitor their environment for data collection or event or object detection purposes. The nodes 104(a)-116(a) and 104(b)-116(b) may process and analyze the data to evaluate the event or the object. The nodes 104(a)-116(a) and 104(b)-116(b) can also transmit collected data to the base station 124(a) and 124(b), respectively, for analysis or storage.
FIG. 2 is a block diagram of one of the nodes 104(a)-116(a) and 104(b)-116(b) (shown in FIGS. 1(a) and 1(b)) in more detail. For ease of description, the node of FIG. 2 will be designated as the node 104. The node 104 includes sensor modules 204, 208, 212, 216 connected to a central processor 224. The sensor modules 204-216 sense the environment for data collection or event or object detection purposes. The sensor modules 204-216 typically do not have capability to process and analyze the data. Accordingly, the data collected by the sensor modules 204-216 are transmitted to the central processor 224. The central processor 224 processes the data to evaluate the event or the object. The node 104 transmits the processed data to the base station 124(a) or 124(b) (shown in FIGS. 1(a) and 1(b)) for storage and/or further analysis.
At present, two system level architectures are used for the wireless sensor network node. The first architecture incorporates an optimized, less powerful system that is specific to a single application. The first architecture generally includes a less powerful (i.e., low processing power), optimized central processor that is designed or chosen only for a specific application. Since the first architecture is specific to a single application, it is inflexible and cannot be extensively modified for other applications. For example, a wireless sensor network node may be designed exclusively for seismic applications. The central processor can be designed or chosen for only seismic related applications including processing and analyzing seismic data, and therefore the central processor need not be a powerful processor. Since these specific central processors typically have low processing power, they consume relatively less power.
The second architecture incorporates a non-optimal, more powerful system that can be adapted for different applications. The second architecture includes a powerful central processor that can be used for different applications. Since the second architecture can be used for different applications, it is flexible. For example, a wireless sensor network node can be designed to monitor seismic events, radiation, or atmospheric pressure and temperature in different applications. The central processor is designed or chosen to be more general, flexible, and computationally powerful to process different types of data, and therefore the central processor needs to be a powerful processor (i.e., high processing power). Since the central processor must possess high processing power, it consumes a large amount of power.
The first architecture, which is the inflexible system, is generally a one time solution. The first architecture cannot be extensively adapted to different applications, but consumes relatively small amounts of power. The second architecture, which is the flexible system, consumes large amounts of power, but can be adapted to different applications. The second architecture is unsuitable for applications in locations where the sensor network node 104 (shown in FIG. 2) must operate on a limited power supply such as battery power. Thus, neither of these systems is satisfactory to produce efficient and flexible sensor systems.
Furthermore, the two architectures are essentially implemented around a central processor. The central processor is typically a microprocessor that performs all functions of the nodes. The central processor is required to perform complicated tasks as well as simple tasks simultaneously. For example, the central processor is required to perform complicated tasks such as processing and analysis of the sensed data, and also perform simple tasks related to the management and control of the node 104 including polling of the sensors 204-212. Thus, the two architectures utilize the central processor inefficiently.
Accordingly, there is a need for a wireless sensor network node system that is flexible and adaptable, yet that does not consume large amounts of power and is efficient for general use.